(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/server/lib/ISandbox.ts

@@ -0,0 +1,28 @@
+import * as log from 'app/server/lib/log';
+
+/**
+ * Starting to whittle down the options used when creating a sandbox, to leave more
+ * freedom in how the sandbox works.
+ */
+export interface ISandboxCreationOptions {
+  comment?: string;      // an argument to add in command line when possible, so it shows in `ps`
+
+  logCalls?: boolean;
+  logMeta?: log.ILogMeta;
+  logTimes?: boolean;
+
+  // This batch of options is used by SafePythonComponent, so are important for importers.
+  entryPoint?: string;   // main script to call - leave undefined for default
+  sandboxMount?: string; // if defined, make this path available read-only as "/sandbox"
+  importMount?: string;  // if defined, make this path available read-only as "/importdir"
+}
+
+export interface ISandbox {
+  shutdown(): Promise<unknown>;  // TODO: tighten up this type.
+  pyCall(funcName: string, ...varArgs: unknown[]): Promise<any>;
+  reportMemoryUsage(): Promise<void>;
+}
+
+export interface ISandboxCreator {
+  create(options: ISandboxCreationOptions): ISandbox;
+}